Method of transferring load in making bridges and the like



Oct. 4, 1932.

' (.1. C. SUNDERLAND METHOD OF TRANSFERRING LOAD IN MAKING BRIDGES AND THE LIKE Filed Jan. 9. 1951 2 Sheets-Sheet Oct. 4, 1932. c. C.SUNDERLAND 1,880,290

METHOD CF TRANSFERRING LOAD IN MAKING BRIDGES AND THE LIKE Filed Jan; 9, 1931 2 Sheets-Sheet 2 i I n I l I l 1 m INVENTOR BY ATTORNEYS to the plane of the other cables and secure the suspension loops to thebridge structure.

Patented Oct. 4, 1932 UNEE v srA'rEs PATEN teas":

,o-F -s CHARLES Ci SUNDERLAND, OF: NEW-BRUNSWICK-NEW J'ERSEY,IASSIG1\T OR TOVJ OHN A.

ROEBLINGS SONS COMPANY, OF.TRE1\TTON, NEW JERSEY',"A CORPORATION OF NEW JERSEY METHOD or rnansrnnniive Loan IN -MAKING BRIDGESAND- THE LIKE Application filed January 9, iaai serial no somaa This invention relates to-that method ofsuspension bridge constructiomin which part of the bridge cables are first laidandsupport the bridge structure during construction ofthe latter, and after the completionofthe brid e structure and the other cables,the

bridge load is transierred to all the cables.

This avoids the delay incident to first laying all the cables and then building the sus-' pended bridge structureon them, In this old method oi construction assumlng a four cable brid 'e, two cables usually are first laid and support the bridge structure during construction, and during such construction the other two cables are laid above the two cables been to run suspension-loopsover the upper cables which are not bearing any, of the bridge load, and by jacks on each suspension loop, operated either bypower-or by hand operated ratchets, pull the upper cables down The release of the jacksthen puts a part of the weight, supposedly one half the weight of the bridge structure, uponv the upper cables, thus relieving the cables first land of one half the weight ofthe bridge structure,

with the result that all the load of the suspended bridge structure is thus transferred tor-all the cables and they rise to their final position. v

The above old method of transferringthe load from part to all of the cables, islvery expensive and not satisfactory, because it is. not possible to be certain as to the ap'proxl-v mately equal divisionoi the load between he four cables, exceptby tests and adjust ments whichinvolve large expense and diificulty.

The present invention relates to a new. 4

for loading all the cables equally;

- may be and convenient determination 'ofthe weight In accordance with the present "invention, the bridge or'similar CO-HStI HOtIOH; proceeds up to the completion of the bridge structure and upper cables in the same manner as above described, but the load is then transferred 5 ,from the'lower cable or cablesto the upper cable orcables by loading" the suspension loops from the-upper cables by water tanks for thefull weight or desired portion of the weight of the bridge structure, and the prop- F er portion of the load is t'ransferred from the lower to the upper cables by the release off the water from the tanks and their removal, when the cables andubridge structure will take their normal and intended position, each" hearing its proper portion'of the load, which adjusted accurately byJthe accurate of water used in'addition to the tanks. The

method is applicable with two or any larger '1 number of cables and with any portion of the cables supporting the bridge structure during construction.

For a full unde'rstandingof the invention a description of preferred methods embodye 7 ing' the invention-will now be given in coni' vnection with the accompanying .drawings forming a part of this specification, and showing the means for carrying? out the method in connection with atfour cable 'suspension bridge, and thefeatures forming the invention will thenbe specifically pointed out in the claims;

Inthe drawings: i c Figure 1 is a diagrammatic'side elevation of a bridge structure with the-upper cables" in position and tanks attached for loading 1 them; 7 V v Figure 2"is a diagrammatic cross section looking to'the left from-line 2 of Figure 1'; Figure 3 is a view similar to Figure 2, show- Y ingin full lines the cables in position ready fortransfer of load by release ofthe water inthe tanks and removal of the tanks and-in" dotted'lines'theposition of the cables after the transfer ofbridge loadto allof the cables; Figures 4,5 and Gare diagrammatic views similartoFigures 2 and- 8 illustrating a modified-methodembodyingthe invention and in V which -'lessweigl1t of tanks and wateris re" quired, Figure showing the cables and bridge structure in their position with the upper cables ready for transfer of load, Figure 5 showing a part of the load transferred to the upper cables and Figure 6 showing the final position of the cables and bridge structure with the load borne equally by all the cables.

. In the drawings, A arethe bridge towers, between which the bridge structure B is suspended by the four cables a ,a a a 10 are suspension loops hung over the upper and lower cables by which the bridge-structure is supported, the suspension loops over the .upper cables carrying temporarily for transfer of load, water tanks 11, and which suspension loops are all connected to the bridge structure finally by connections as indicated at 12. V

In carrying out the method as illustrated in Figures 1 to 3, and assuming that the bridge structure involves a load of 480,000 pounds, this entirebridge load will be carried during construction by cables a a each carrying 240,000 pounds, as shown in Figures 1 and 2, and the cables a a in these figures are carrymg no bridge load. For the transfer of the load from ,cablesa a to all the cables, the tanks ll'on the cables a a are applied on the suspension loops and supplied with water until the loadon these cables is the same as on cables a a that is, 240,000 pounds on each cable, which will lower the cables 04 a into the plane of the cables a a as shown in full lines in Figure. 3. In this position of cables at, a, they are secured to the bridge structure, as indicated by the connections 12, and the water is then released from the tanks and the tanks'removed from the suspension loops, the cables a a? thentakingone half of the bridge load, that'is, 210,000 pounds or 120,000 pounds each and cables of, a 61 ,61 with the bridge structure rising to their final position shown by dotted lines in Figure 5.

The method illustrated in Figures e1, 5 and 6 employs the same principle as that illustrated in Figures l to 3 and above described,

but only a portion of the final load on the upper cables is applied in the tanks and water,

:and the load istransferred to the upper cables intwo steps,vpar,t of the required load being first transferred to the upper cables and then the remaining portion of such load.

In Figure 4, the cables and bridge structure are shown'in their position with the lower cables a a? carrying the full bridge load, and the upper cables a a carrying no load. The upper. cables a a are now connected to the bridge structure and to the tanks 11 by connecting to suspension loops 10 on cables a end of which cables 13 is secured to the bridge structure as at 1, and the other end connected to a water tank 11 and the tanks are then to the cables a a, this load thus bringing the cable a a into the same plane as cables a a which, with the bridge structure, rise somewhat on the release from them of part of the bridge load thus transferred to the cables a a.

Assuming that 160,000 pounds of the total bridge load of 480,000 pounds is thus trans load is thus transferred equally to all the four cables, the cables and bridge structure then rising into their final position with each cable supporting 120,000 pounds load, as indicated in Figure 6. V

The method illustrated in Figures 4 to 6 will usually be found preferable to that illustrated in Figures 1 t0 3, because of the less outside weight to be provided on the upper 7 cables for transfer of load, but either of these methods will be found; simple, cheap and quick as compared with previous methods used in such load transfer.

It will be understood that the invention is not limited to the details of either of the methods illustrated and above described, but that such method may readily be modified by those skilled in the art, While retaining the invention defined by'the claims.

ll hat I claim is: v

1. The method of transferring a bridge load from some to all of the bridge supporting cables, which consists in first supporting the bridge, structureby a lower cable or cables, then loading the upper cable or cables with weights equivalent to the bridge load or a desired part thereof, and then connecting the weight loaded cable or cables to the bridge structure for supporting the latter, and removing the weights. 7 2. The method of transferring abridge load from some to all of the bridge supporting. cables, which consists in first supporting the bridge structure by a lower cable or cables, then loading the upper cable or cables with weights consisting of tanks and liquid equivalentto the bridge load or a desired part there- 'of, and then connecting the weight loaded cable or cables to the bridge structure for supportlng the latter, and drawing off the liquid from the tanks.

In testimony whereof, I have hereunto set my hand. a, sheaves 13, over wh1ch run cables 14, one

oi-rAntns o. SUNDERLAND,

filled with water to transfer a part of the load 1 

